1. Field of the Invention
This invention relates in general to the field of connecting or clamping devices and more particularly to a means for joining two tubular conduits of different outside diameters.
2. Description of the Prior Art
There are various prior art situations in which the invention is usable or applicable, such as tubing and hoses of widely varying compositions and sizes, rigid tube and flexible hose combinations, transfer systems in which a solid particle media such as grain or feed is transferred from one point or container to another, and the exhaust systems of trucking equipment. In this latter application, one tubular member may be conventionally inserted into another and secured there by tightening a U-bolt against a semi-circular shoe. This clamping arrangement has the drawback that it deforms the cross sections of the tubes from circular to elliptical, so that stresses are not uniform and so that gas and sound leaks frequently result. A further defect of the arrangement is that the narrow U-bolt frequently dimples the outer tubular member into the inner one, in such a fashion that when the U-bolt is removed, it is impossible to disassemble the complete system without cutting the metal. Again, the U-bolt arrangement is very severe in its action on flexible metal hose, while at the same time being relatively inefficient in preventing leaks along the helical grooves in such hoses. In a grain or feed transfer, where gas and sound leaks are not a factor, this non-uniformity of stresses may still cause premature failure of the connection.
Efforts have been made to overcome the defects of U-bolt type clamps by use of a ductile metal band placed in direct contact with both tubular members and then circumferentially stressed causing the band to conform to the surfaces of the members. To achieve a suitable, gas-tight seal, this method requires that the metal band be stressed beyond its elastic limit.
This ductile band method employs rectangular, reinforced bars secured to the ends of the ductile band with a substantially straight longitudinal edge located toward the axis of the members. When the surfaces of the bars are drawn into mutual flat contact with each other and secured there with a nut and bolt arrangement, the ductile band forms a sealed joint around the tubular members. This method works well with tubular members having the same outside diameter because virtually the entire longitudinal edge of each bar will be drawn into contact with the band and tubular members. This longitudinal contact both reduces stress in the band as well as improves the overall strength of the connection. However, when tubular members of different outside diameters are attempted to be connected, the use of this type of reinforcing bar presents certain disadvantages. As the bars are drawn together into mutual flat contact, the ductile band is stressed to a greater extent around the larger of the two tubular members so that by the time a sealed joint is achieved around the smaller member, the ductile band has been stressed well beyond its elastic limit in the area of the larger member. In addition, the overlap of the joint causes the first end of the bar adjacent the smaller tubular member to have only a single point of contact to the member. Thus, as the bars are drawn together, a line of stress concentration develops at this point and moves from the first end to the opposite end. The end of the bar adjacent the smaller member will not be able to achieve complete longitudinal edge contact against the member, and the result is a connection in which the ductile band is stressed beyond its elastic limit in some areas and has a non-uniform stress pattern in other areas.
The following prior art is known to exist:
U.s. pat. No. 3,944,265--Hiemstra et al. PA1 U.s. pat. No. 1,146,813--Peterman et al. PA1 U.s. pat. No. 1,594,258--Hansen PA1 U.s. pat. No. 2,227,551--Morris PA1 U.s. pat. No. 2,314,236--Mott PA1 U.s. pat. No. 2,713,352--Schustack PA1 U.s. pat. No. 2,787,051--Risley PA1 U.s. pat. No. 3,087,221--Armstrong PA1 U.s. pat. No. 3,216,079--Keyworth PA1 U.s. pat. No. 3,411,748--Fortune PA1 U.s. pat. No. 3,708,834--Anderson et al. PA1 U.s. pat. No. 3,847,419--Brown